The order of basic character among NH3,PH3,AsH3,SbH3,BiH3 ? Why are penta bromides and penta Iodides of group 15 elements unstable? Why does not Bi form Penta halides? Does N2 show allotropy?

jee king king Grade: 12

        

The order of  basic character among NH3,PH3,AsH3,SbH3,BiH3 ?

Why are penta bromides and penta Iodides of group 15 elements unstable? Why does not Bi form Penta halides?

Does N2 show allotropy?

8 years ago

Answers : (2)

ruchi yadav

askIITians Faculty

26 Points

										the basic character of hydrides decreases as follows:
NH3>PH3>AsH3>SbH3>BiH3

all hydrides of group 15 element possesses a lone pair of electrons on central atom and thus behave as lewis bases..
NH3 is basic and forms salt with strong and weak acids...PH3 is a very weak base(may even be regarded as neutral)and thus forms salt with anhydrous hydrochloric acid gas...AsH3,SbH3 and BiH3 are not at all basic...
the reason for such trend is : as the size of central atom increases..the lone pair of electron occupies a larger volume ..in other words electron density on central atom decreases and consequently its tendency to donate a pair of electron decreases and hence its basic strength decreases as we move from NH3 to BiH3..
as basic strength is in that order so acidic strength order will be the reverse of that:
BiH3>SbH3>AsH3>PH3>NH3

Thank You
Ruchi
Askiitians Faculty

4 years ago

Mainak

13 Points

										The thing is NH3 due to it`s small size which is one of the analogous property and high electronegativity  has the lone pairs in a smaller volume ..... Since all the elements in the respective group have 5 electrons ... Out of which

7 months ago

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